(1) Field of the Invention
The present invention relates to a semiconductor device using a ferroelectric material or a high-dielectric-constant material for a capacitive insulating film.
(2) Description of Related Art
Semiconductor devices each using a ferroelectric material or a high-dielectric-constant material for a capacitive insulating film of a capacitor may be replaced with semiconductor devices each having a capacitive insulating film made of silicon oxide or silicon nitride in the field of non-volatile memory devices and dynamic random access memory (DRAM) devices. The reason for this is that ferroelectric materials and high-dielectric-constant materials exhibit residual polarization arising from hysteresis characteristics and have a high dielectric constant.
Typically, reduction action caused by hydrogen allows ferroelectric materials or high-dielectric-constant materials to have deteriorated characteristics, because ferroelectric materials or high-dielectric-constant materials are oxides whose crystal structures themselves determine their physical characteristics. In spite of this, a process of forming a MOS transistor, a process of forming a multilayer interconnect, a process of forming a protective film, and other processes include many process steps using not only a hydrogen gas but also a silane gas, a resist material and water (moisture) all containing hydrogen atoms.
For example, Japanese Unexamined Patent Publications Nos. 11-126881 and 2001-237393 disclose as follows: as shown in FIGS. 5 and 6, in order to prevent a ferroelectric material or a high-dielectric-constant material from being deteriorated in its characteristics in each of production processes due to hydrogen, a ferroelectric capacitor is covered with hydrogen barrier films located above and below the ferroelectric capacitor; and the hydrogen barrier films are formed to enclose the ferroelectric capacitor therein.